The invention relates to a method and an apparatus for the modulated raising of the carriages by which a wind-up roll held on stub shafts inserted into its core tube is carried for vertical displacement in the centerless winding of webs, while a pressure cylinder lies axially parallelly on the wind-up roll.
In the centerless winding of webs of paper, textiles or plastics, the roll being wound lies on two supporting cylinders of which at least one is driven in rotation. After the leading end of the web has been attached to the wind-up roll core tube, the supporting cylinder or cylinders are set in rotation thereby causing the wind-up roll lying axially parallel on their circumference also to rotate. To control the winding tightness, a pressure cylinder lies on the outer circumference of the wind-up roll axially parallel thereto, for the purpose of the uniform winding of the wind-up roll so as to prevent the formation of wrinkles.
To prevent the wind-up roll from creeping in the axial direction and to achieve an accurately positioned winding of the wind-up roll, lateral guides are provided in which carriages can travel or be displaced vertically and which are joined to the wind-up roll by means of stub shafts inserted into the core tube.
As the winding progresses, the axis of the wind-up roll rises, and especially in the case of rolls which are much narrower than the nominal working width of the winding machine the carriages can jam because the lever arm (the distance between the carriage and the end of the wind-up roll) is great and the stub shaft become cocked causing interference between the carriage and its track.
To counteract these difficulties, it is known to make the carriages follow the movement of the wind-up roll through the use of an independent drive in the form of air cylinders or hydraulic cylinders, for example. This, however, is a very expensive and complex method. Furthermore, the carriages can still jam, because the known drives operate according to their own peculiar laws of motion, not according to the law of motion of the growing wind-up roll.